Carbinol-terminated polymers containing amine

ABSTRACT

The present invention relates to diene polymers, wherein the diene polymers have, at the start of the polymer chains, tertiary amino groups of the formula (I) or (II) 
     
       
         
         
             
             
         
       
     
     where
         R 1 , R 2  are the same or different and are each alkyl, cycloalkyl, aryl, alkaryl and aralkyl radicals which may contain heteroatoms such as O, N, S and/or Si,   Z is a divalent organic radical which, as well as C and H, may contain heteroatoms such as O, N, S and/or Si,
 
and, at the end of the polymer chains, silane-containing carbinol groups of the formula (III)
       

     
       
         
         
             
             
         
       
     
     or metal salts thereof or semimetal salts thereof, where
         R 3 , R 4 , R 5 , R 6  are the same or different and are each an H or alkyl, cycloalkyl, aryl, alkaryl and aralkyl radicals which may contain heteroatoms such as O, N, S and/or Si,   A is a divalent organic radical which, as well as C and H, may contain heteroatoms such as O, N, S and/or Si.

The invention relates to diene polymers with functionalizations at thestart of the polymer chains and at the end of the polymer chains, and tothe preparation and use thereof.

Important properties desirable in tyre treads include good adhesion ondry and wet surfaces, and high abrasion resistance. It is very difficultto improve the skid resistance of a tyre without simultaneouslyworsening the rolling resistance and abrasion resistance. A low rollingresistance is important for low fuel consumption, and high abrasionresistance is a crucial factor for a long lifetime of the tyre.

Wet skid resistance and rolling resistance of a tyre tread dependlargely on the dynamic/mechanical properties of the rubbers which areused in the blend production. To lower the rolling resistance, rubberswith a high resilience at higher temperatures (60° C. to 100° C.) areused for the tyre tread. On the other hand, for lowering of the wet skidresistance, rubbers having a high damping factor at low temperatures (0to 23° C.) or low resilience in the range of 0° C. to 23° C. areadvantageous. In order to fulfil this complex profile of requirements,mixtures of various rubbers are used in the tread. Usually, mixtures ofone or more rubbers having a relatively high glass transitiontemperature, such as styrene-butadiene rubber, and one or more rubbershaving a relatively low glass transition temperature, such aspolybutadiene having a high 1,4-cis content or a styrene-butadienerubber having a low styrene and low vinyl content or a polybutadieneprepared in solution and having a moderate 1,4-cis and low vinylcontent, are used.

Anionically polymerized solution rubbers containing double bonds, suchas solution polybutadiene and solution styrene-butadiene rubbers, haveadvantages over corresponding emulsion rubbers in terms of production oftyre treads with low rolling resistance. The advantages lie, inter alia,in the controllability of the vinyl content and of the associated glasstransition temperature and molecular branching. In practical use, thesegive rise to particular advantages in the relationship between wet skidresistance and rolling resistance of the tyre. Important contributionsto energy dissipation and hence to rolling resistance in tyre treadsresult from free ends of polymer chains and from the reversible buildupand degradation of the filler network formed by the filler used in thetyre tread mixture (usually silica and/or carbon black).

The introduction of functional groups at the start of the polymer chainsand/or end of the polymer chains enables physical or chemical attachmentof the start of the chains and/or end of the chains to the fillersurface. This restricts the mobility thereof and hence reduces energydissipation under dynamic stress on the tyre tread. At the same time,these functional groups can improve the dispersion of the filler in thetyre tread, which cars lead to a weakening of the filler network andhence to further lowering of the rolling resistance.

Methods for introducing functional groups at the start of polymer chainsby means of functional anionic polymerization initiators are described,for example, in EP 0 513 217 B1 and EP 0 675 140 B1 (initiators with aprotected hydroxyl group), US 2008/0308204 A1 (thioether-containinginitiators) and in U.S. Pat. No. 5,792,820 and EP 0 590 490 B1 (alkalimetal amides of secondary amines as polymerization initiators).

More particularly, EP 0 594 107 B1 describes the in situ use ofsecondary amines as functional polymerization initiators, but does notdescribe the chain end functionalization of the polymers.

In addition, numerous methods have been developed for introduction offunctional groups at the end of polymer chains. For example, EP 0 180141 A1 describes the use of 4,4′-bis(dimethylamino)benzophenone orN-methylcaprolactam as functionalization reagents. The use of ethyleneoxide and N-vinylpyrrolidone is known from EP 0 864 606 A1. A number offurther possible functionalization reagents are detailed in U.S. Pat.No. 4,417,029.

Especially silanes having a total of at least two halogen and/oralkyloxy and/or aryloxy substituents on silicon are of good suitabilityfor functionalization at the ends of the polymer chains of dienerubbers, since one of the said substituents on the silicon atom can bereadily exchanged for an anionic diene polymer chain end and the furtheraforementioned substituent(s) on Si is/are available as a functionalgroup which, optionally after hydrolysis, can interact with the fillerof the tyre tread mixture. Examples of such silanes can be found in U.S.Pat. No. 3,244,664, U.S. Pat. No. 4,185,042, EP 0 890 580 A1.

However, many of the reagents mentioned for functionalization at theends of the polymer chains have disadvantages, for example poorsolubility in the process solvent, high toxicity or high volatility,which can lead to contamination of the recycled solvent. In addition,many of these functionalization reagents can react with more than oneanionic polymer chain end, which leads to coupling reactions which areoften troublesome and difficult to control. This is particularly true ofthe silanes mentioned. These also have the further disadvantage thatreaction of these silanes with the anionic end of the polymer chaineliminates components such as halides or alkoxy groups, the latter beingreadily convertible to alcohols. Halides promote corrosion; alcohols canlead to contamination of the process solvent. A further disadvantage ofthe use of silanes as functionalization reagents is that thesiloxane-terminated polymers obtained therefrom, after functionalizationvia the Si—OR groups at the ends of the polymer chains (or via the Si—OHgroups after hydrolysis of the Si—OR groups), can couple to form Si—O—Sibonds, which leads to an unwanted rise in viscosity of the rubbersduring processing and storage. Many methods for reducing this rise inviscosity in siloxane-terminated polymers have been described, forexample the addition of stabilizing reagents based on acid and acidhalides (EP 0 801 078 A1), addition of siloxane (EP 1 198 506 B1),addition of long-chain alcohols (EP 1 237 934 B1) or addition ofreagents to control the pH (EP 1 726 598).

EP 0 778 311 B1 describes, inter alia, cyclosiloxanes asfunctionalization reagents for introduction of Si—OH groups at the endsof the polymer chains. These cyclosiloxanes have the advantage over theabovementioned silanes that only one anionic end of the polymer chain ineach case can react per cyclosiloxane molecule. Thus, during thefunctionalization reaction, no couplings take place through addition ofmore than one polymer chain per functionalization reagent. The Si—OH endgroups formed after introduction of the functionalization reagents can,however, as explained above and also described in U.S. Pat. No.4,618,650, couple to form Si—O—Si bonds. Mere too, there is thus theproblem of the unwanted rise in viscosity during processing and storage.

It was therefore an object of the present invention to providefunctionalized polymers which do not have the disadvantages of the priorart, and more particularly enable utilization, of the good reactivity ofsilanes having anionic ends of the polymer chains without having thedisadvantages thereof, for instance reaction of several anionic ends ofpolymer chains per silane molecule, elimination of troublesomecomponents and coupling to form Si—O—Si bonds in the course ofprocessing and storage.

For achievement of this object, functionalized diene polymers areproposed, these having, at the start of the polymer chains, tertiaryamino groups of the formula (I) or (II)

where

-   -   R¹, R² are the same or different and are each alkyl, cycloalkyl,        aryl, alkaryl and aralkyl radicals which may contain heteroatoms        such as O, N, S and/or Si,    -   Z is a divalent organic radical which, as well as C and H, may        contain heteroatoms such as O, N, S and/or Si,        and, at the end of the polymer chains, silane-containing        carbinol groups of the formula (III)

or metal salts thereof or semi metal salts thereof, where

-   -   R³, R⁴, R⁵, R⁶ are the same or different and are each an H or        alkyl, cycloalkyl, aryl, alkaryl and aralkyl radicals which may        contain heteroatoms such as O, N, S and/or Si,    -   A is a divalent organic radical which, as well as C and H, may        contain heteroatoms such as O, N, S and/or Si.

Preferably, the silane-containing carbinol groups of the formula (III)at the end of the polymer chains of the inventive functionalized dienepolymers may be in the form of metal salts of the formula (IV):

where

-   -   R³, R⁴, R⁵, R⁵ are the same or different and are each H, alkyl,        cycloalkyl, aryl, alkaryl and aralkyl radicals which may contain        heteroatoms such as O, N, S and/or Si,    -   A is a divalent organic radical which, as well as C and H, may        contain heteroatoms such as O, N, S and/or Si,    -   n is an integer from 1 to 4,    -   M is a metal or semimetal of valency 1 to 4, preferably Li, Na,        K, Mg, Ca, Fe, Co, Ni, Al, Nd, Ti, Si and/or Sn.

Preferred polymers for preparation of the inventive functionalized dienepolymers are diene polymers, and diene copolymers obtainable bycopolymerization of dienes with vinylaromatic monomers.

Preferred dienes are 1,3-butadiene, isoprene, 1,3-pentadiene,2,3-dimethylbutadiene, 1-phenyl-1,3-butadiene and/or 1,3-hexadiene.Particular preference is given to using 1,3-butadiene and/or isoprene.

The vinylaromatic comonomers may, for example, be styrene, o-, m- and/orp-methylstyrene, p-tert-butylstyrene, α-methylstyrene, vinylnaphthalene,divinylbenzene, trivinylbenzene and/or divinylnaphthalene. Particularpreference is given to using styrene.

These polymers are preferably prepared by anionic solutionpolymerization.

Initiators for the anionic solution polymerization are alkali metalamides of secondary organic amines, for example lithium pyrrolidide,lithium piperidide, lithium hexamethyleneimide, lithium1-methylimidazolidide, lithium 1-methylpiperazide, lithium morpholide,lithium diphenylamide, lithium dibenzylamide, lithium dicyclohexylamide,lithium dihexylamide, lithium dioctylamide. In addition, it is alsopossible to use difunctional alkali metal amides, for example dilithiumpiperazide.

These alkali metal amides are preferably prepared by reaction of thecorresponding secondary amines with organo-alkali metal compounds.Preferred organo-alkali metal compounds for this purpose, aren-butyllithium and sec-butyllithium. The alkali metal amides arepreferably prepared in situ in the polymerization reactor by reaction ofan organo-alkali metal compound with secondary amines. Preferredsecondary amines are pyrrolidines, piperidines, hexamethyleneimines,1-alkylimidazolidines, 1-alkylpiperazines, morpholines,N,N-diphenylamines, N,N-dibenzylamines, N,N-dicyclohexylamine,N,N-dihexylamine, N,N-dioctylamine.

In addition, it is possible to use the brown randomizers and controlagents for the microstructure of the polymer, for example diethyl ether,di-n-propyl ether, diisopropyl ether, di-n-butyl ether, ethylene glycoldimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-butylether, ethylene glycol di-tert-butyl ether, diethylene glycol dimethylether, diethylene glycol diethyl ether, diethylene glycol di-n-butylether, diethylene glycol di-tert-butyl ether,2-(2-ethoxyethoxy)-2-methylpropane, triethylene glycol dimethyl ether,tetrahydrofuran, ethyl tetrahydrofurfuryl ether, hexyltetrahydrofurfuryl ether, 2,2-bis(2-tetrahydrofuryl)propane, dioxane,trimethylamine, triethylamine, N,N,N′,N′-tetramethylethylenediamine,N-methylmorpholine, N-ethylmorpholine, 1,2-dipiperidinoethane,1,2-dipyrrolidinoethane, 1,2-dimorpholinoethane and potassium and sodiumsalts of alcohols, phenols, carboxylic acids, sulphonic acids.

Such solution polymerizations are known and are described, for example,in I. Franta, Elastomers and Rubber Compounding Materials; Elsevier1989, pages 113-131, in Houben-Weyl, Methoden der Organischen Chemie[Methods of Organic Chemistry], Thieme Verlag, Stuttgart, 1961, volumeXIV/I pages 645 to 673 or in volume E 20 (1987), pages 114 to 134 andpages 134 to 153, and in Comprehensive Polymer Science, Vol 3, Part I(Pergamon Press Ltd., Oxford 1989), pages 365-386.

The preparation of the preferred diene polymers preferably takes placein a solvent. The solvents used for the polymerization are preferablyinert aprotic solvents, for example paraffinic hydrocarbons, such asisomeric butanes, pentanes, hexanes, heptanes, octanes, decanes,cyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane or1,4-dimethylcyclohexane or aromatic hydrocarbons, such as benzene,toluene, ethylbenzene, xylene, diethylbenzene or propylbenzene. Thesesolvents can be used individually or in combination. Preference is givento cyclohexane and n-hexane. Blending with polar solvents is likewisepossible.

The amount of solvent in the process according to the invention istypically 100 to 1000 g, preferably 200 to 700 g, based on 100 g of thetotal amount of monomer used. However, it is also possible to polymerizethe monomers used in the absence of solvents.

The polymerization can be performed in such a way that the monomers,optionally control agents to adjust the microstructure and the solventsare initially charged and then the polymerization is started by addingthe initiator. Polymerization in a feed process is also possible, inwhich the polymerization reactor is filled by addition of monomers,optionally control agents to adjust the microstructure and solvents, theinitiator being initially charged or added with the monomers, optionallycontrol agents to adjust the microstructure and the solvent. Variationsare possible, such as initial charging of the solvent in the reactor,addition of the initiator and then addition of the monomers andoptionally control agents to adjust the microstructure. In addition, thepolymerization can be operated in a continuous mode. Further addition ofmonomer, control agent and solvent during or at the end of thepolymerization is possible in all cases.

In a preferred embodiment, the monomers, optionally control agents toadjust the microstructure, the solvent and a secondary amine areinitially charged, and the polymerisation is started by addition of anorgano-alkali metal compound, such as BuLi, with formation of the alkalimetal amide initiator in situ through reaction of the organo-alkalimetal compound with the secondary amine.

The polymerization time may vary within wide limits from a few minutesto a few hours. Typically, the polymerization is performed within aperiod of about 10 minutes up to 8 hours, preferably 20 minutes to 4hours. It can be performed either at standard pressure or at elevatedpressure (1 to 10 bar).

It has been found that, surprisingly, through the use of alkali metalamide polymerization initiators for introduction of tertiary aminogroups at the start of the polymer chains in combination with the use ofone or more 1-oxa-2-silacycloalkanes as functionalization reagents forintroduction of functional groups at the end of the polymer chains, itis possible to prepare diene polymers which have improved tyre treadproperties and do not have the disadvantages of the prior art. Forexample, couplings through multiple reactions of the functionalizationreagent, elimination of troublesome components and couplings throughformation of Si—O—Si bonds in the course of workup and storage cannottake place.

The alkali metal amide polymerization initiators are compounds of thegeneral formula (V) or (VI)

where

-   -   R¹, R² are the same or different and are each alkyl, cycloalkyl,        aryl, alkaryl and aralkyl radicals which may contain heteroatoms        such as O, N, S and/or Si,    -   Z is a divalent organic radical which, as well as C and H, may        contain heteroatoms such as O, N, S and/or Si,    -   M is Li, Ma, K.

The 1-oxa-2-silacycloalkanes are compounds of the general formula (VII)

where

-   -   R³, R⁴, R⁵, R⁶ are the same or different and are each H, alkyl,        cycloalkyl, aryl, alkaryl and aralkyl radicals which may contain        heteroatoms such as O, N, S and/or Si,    -   A is a divalent organic radical which, as well as C and H, may        contain heteroatoms such as O, N, S and/or Si.

The silicon atom of the formula (VII) is monofunctional,“monofunctional” being understood to mean that the silicon atom hasthree Si—C bonds and one Si—O bond.

Examples of compounds of the formula (VII) are:

It has been found that the inventive functionalized diene polymers canbe prepared by reaction of reactive ends of polymer chains with1-oxa-2-silacycloalkanes and optional subsequent protonation of thealkoxide end group to give the alcohol.

Thus, the invention also provides for the use of1-oxa-2-silacycloalkanes as funtionalization reagents for preparation ofthe inventive functionalized diene polymers having end groups of theformula (III) or (IV).

The inventive functionalized diene polymers preferably have mean molarmasses (number-average) of 10000 to 2000000 g/mol, preferably 100000 to1000000 g/mol, and glass transition temperatures of −110° C. to +20° C.,preferably −110° C. to 0° C., and Mooney viscosities ML 1+4 (100° C.) of10 to 200, preferably 30 to 150, Mooney units.

The invention further provides a process for preparing the inventivefunctionalized diene polymers, according to which alkali metal amides ofsecondary organic amines are used as polymerization initiators, as areone or more compounds of the formula (VII), as a pure substance,solution or suspension, for reaction with the reactive ends of thepolymer chains. The compounds of the formula (VII) are preferably addedafter the polymerization has concluded, but they can also be added priorto complete monomer conversion. The reaction of compounds of the formula(VII) with the reactive ends of the polymer chains is effected at thetemperatures customarily used for the polymerization. The reaction timesfor the reaction of compounds according to formula (VII) with thereactive ends of the polymer chains may be between a few minutes andseveral hours.

The alkali metal amides used are preferably in solution. Preference isgiven to using the same solvent which is also used for thepolymerization. However, it is also possible to use solvents or solventmixtures with relatively high polarity, in order to preventprecipitation of the alkali metal amides.

Preference is given to a process for preparing the inventivefunctionalized diene polymers in which the polymerization initiators areobtained by reaction of secondary amine with organo-alkali metalcompounds in a separate preforming step or in situ directly in thepolymerization reactor for formation of alkali metal amides, and one ormore compounds of the formula (VII) are used, as a pure substance,solution or suspension, for reaction with the reactive ends of thepolymer chains. The compounds of the formula (VII) are preferably addedafter the polymerization has concluded, but they can also be added priorto complete monomer conversion. The reaction of compounds of the formula(VII) with the reactive ends of the polymer chains is effected at thetemperatures customarily used for the polymerization. The reaction timesfor the reaction of compounds according to formula (VII) with thereactive ends of the polymer chains may be between a few minutes andseveral hours.

The amount of secondary amines is preferably less than or equal to theamount of organo-alkali metal compounds, particular preference beinggiven to a molar ratio between secondary amines and organo-alkali metalcompounds of 0.05-2.00:0.05-2.00.

It has been found that, with this ratio, the ends of the polymer chainsare functionalized with silane-containing carbinol compounds, so as toform polymers with functionalization at both ends, these having improvedtyre tread properties, with avoidance of couplings through multiplereactions of the functionalization reagent, elimination of troublesomecomponents and couplings through formation of Si—O—Si bonds in thecourse of workup and storage of the polymers.

The amount of the 1-oxa-2-silacycloalkanes of the formula (VII) can beselected such that all the reactive ends of the polymer chains reactwith compounds of the formula (VII), or it is possible to use adeficiency of these compounds. The amounts of the compounds of formula(VII) used may cover a wide range. The preferred amounts are between0.005-2% by weight, more preferably between 0.01-1% by weight, based onthe amount of polymer.

In addition to compounds of formula (VII), it is also possible to usethe coupling reagents typical of anionic diene polymerization forreaction with the reactive ends of polymer chains. Examples of suchcoupling reagents are silicon tetrachloride, methyltrichlorosilane,dimethyldichlorosilane, tin tetrachloride, dibutylin dichloride,tetraalkoxysilanes, ethylene glycol diglycidyl ether,1,2,4-tris(chloromethyl)benzene. Such coupling reagents can be addedprior to, together with or after the compounds of the formula (VII).

On completion of addition of compounds of the formula (VII) andoptionally of coupling reagents, before or during the workup of theinventive functionalized polymers, preference is given to adding thecustomary ageing stabilizers, such as sterically hindered phenols,aromatic amines, phosphites, thioethers. In addition, it is possible toadd the customary extender oils used for diene ambers, such as DAE(Distillate Aromatic Extract), TDAE (Treated Distillate AromaticExtract), MES (Mild Extraction Solvates), RAE (Residual AromaticExtract), TRAE (Treated Residual Aromatic Extract), naphthenic and heavynaphthenic oils. It is also possible to add fillers, such as carbonblack and silica, rubbers and rubber auxiliaries.

The solvent can be removed from the polymerization process by thecustomary methods, such as distillation, stripping with steam orapplication of reduced pressure, optionally at elevated temperature.

The invention further provides for the use of the inventivefunctionalized polymers for production of vulcanizable rubbercompositions.

These vulcanizable rubber compositions preferably comprise furtherrubbers, fillers, rubber chemicals, processing aids and extender oils.

Additional rubbers are, for example, natural rubber and syntheticrubbers. If present, the amount thereof is preferably within the rangefrom 0.5 to 95%, preferably 10 to 80%, by weight, based on the totalamount of polymer in the mixture. The amount of rubbers additionallyadded is again guided by the respective end use of the inventivemixtures.

Synthetic rubbers known from the literature are listed here by way ofexample. They comprise, inter alia,

-   BR—polybutadiene-   ABR—butadiene/C₁-C₄-alkyl acrylate copolymers-   IR—polyisoprene-   E-SBR—styrene-butadiene copolymers having styrene contents of 1-60%,    preferably 20-50%, by weight, prepared by emulsion polymerization-   S-SBR—styrene-butadiene copolymers having styrene contents of 1-60%,    preferably 15-45%, by weight, prepared by solution polymerization-   IIR—isobutylene-isoprene copolymers-   NBR—butadiene-acrylnitrile copolymers having acrylonitrile contents    of 5-60%, preferably 10-40%, by weight.-   HNBR—partly hydrogenated or fully hydrogenated NBR rubber-   EPDM—ethylene-propylene-diene terpolymers    and mixtures of these rubbers. For the production of car tyres,    particularly natural rubber, E-SBR and S-SBR having a glass    transition temperature above −60° C., polybutadiene rubber which has    a high cis content (>90%) and has been prepared with catalysts based    on Ni, Co, Ti or Nd, and polybutadiene rubber having a vinyl content    of up to 80% and mixtures thereof are of interest.

Useful fillers for the inventive rubber compositions include all knownfillers used in the rubber industry. These include both active andinactive fillers.

The following should be mentioned by way of example:

-   -   finely divided silicas, produced, for example, by precipitation        of solutions of silicates or flame hydrolysis of silicon halides        having specific surface areas of 5-1000, preferably 20-400, m²/g        (BET surface area) and having primary particle sizes of 10-400        nm. The silicas may optionally also be present as mixed oxides        with other metal oxides, such as oxides of Al, Mg, Ca, Ba, Zn,        Zr, Ti;    -   synthetic silicates, such as aluminium silicate, alkaline earth        metal silicates such as magnesium silicate or calcium silicate,        having BET surface areas of 20-400 nm/g and primary particle        diameters of 10-400 nm;    -   natural silicates, such as kaolin and other naturally occurring        silica;    -   glass fibres and glass fibre products (mats, strands) or glass        microspheres;    -   metal oxides, such as zinc oxide, calcium oxide, magnesium        oxide, aluminium oxide;    -   metal carbonates, such as magnesium carbonate, calcium        carbonate, zinc carbonate;    -   metal hydroxides, for example aluminium hydroxide, magnesium        hydroxide;    -   metal sulphates, such as calcium sulphate, barium sulphate;    -   carbon blacks: The carbon blacks to be used here are carbon        blacks produced by the lamp black, channel black, furnace black,        gas black, thermal black, acetylene black or light arc process        and have BET surface areas of 9-200 m²/g, for example SAF,        ISAF-LS, ISAF-HM, ISAF-LM, ISAF-HS, CF, SCF, HAF-LS, HAF,        HAF-HS, FF-HS, SPF, XCF, FEF-LS, FEF, FEF-HS, GPF-HS, GPF, APF,        SRF-LS, SRF-LM, SRF-HS, SRF-HM and MT carbon blacks, or ASTM        N110, N219, N220, N231, N234, N242, N294, N326, N327, N330,        N332, N339, N347, N351, N356, N358, N375, N472, N539, N550,        N568, N650, N660, N754, N762, N765, N774, N787 and N990 carbon        blacks;    -   rubber gels, especially those based on BR, E-SBR and/or        polychloroprene having particle sizes of 5 to 1000 nm.

The fillers used are preferably finely divided silicas and/or carbonblacks.

The fillers mentioned can be used alone or in a mixture. In aparticularly preferred embodiment, the rubber compositions comprise, asfillers, a mixture of light-coloured fillers, such as finely dividedsilicas, and carbon blacks, the mixing ratio of light-coloured fillersto carbon blacks being 0.01:1 to 50:1, preferably 0.05:1 to 20:1.

The fillers are used here in amounts in the range from 10 to 500 partsby weight based on 100 parts by weight of rubber. Preference is given tousing 20 to 200 parts by weight.

In a further embodiment of the invention, the rubber compositions alsocomprise rubber auxiliaries which, for example, improve the processingproperties of the rubber compositions, serve to crosslink the rubbercompositions, improve the physical properties of the vulcanizatesproduced from the inventive rubber compositions for the specific end usethereof, improve the interaction between rubber and filler, or serve forattachment of the rubber to the filler.

Rubber auxiliaries are, for example, crosslinker agents, for examplesulphur or sulphur-supplying compounds, and also reaction accelerators,ageing stabilizers, heat stabilizers, light stabilizers, antiozonants,processing aids, plasticizers, tackifiers, blowing agents, dyes,pigments, waxes, extenders, organic acids, silanes, retardants, metaloxides, extender oils, for example DAE (Distillate Aromatic Extract),TDAE (Treated Distillate Aromatic Extract), MES (Mild ExtractionSolvates), RAE (Residual Aromatic Extract), TRAE (Treated ResidualAromatic Extract), naphthenic and heavy naphthenic oils and activators.

The total amount of rubber auxiliaries is within the range from 1 to 300parts by weight, based on 100 parts by weight of overall rubber.Preference is given to using 5 to 150 parts by weight of rubberauxiliaries.

The vulcanizable rubber compositions can be produced in a one-stage orin a multistage process, preference being given to 2 to 3 mixing stages.For example, sulphur and accelerator can be added in a separate mixingstage, for example on a roller, preferred temperatures being in therange of 30° C. to 90° C. Preference is given to adding sulphur andaccelerator in the last mixing stage.

Examples of equipment suitable for the production of the vulcanizablerubber compositions include rollers, kneaders, internal mixers or mixingextruders.

Thus, the invention further provides vulcanizable rubber compositionscomprising functionalized diene polymers having tertiary amino groups ofthe formula (I) or (II) at the start of the polymer chains andfunctional groups of the formula (III) or (IV) at the end of the polymerchains.

The rubber compositions may also comprise functionalized diene polymershaving tertiary amino groups of the formula (I) or (II) at the start ofthe polymer chains and functional groups of the formula (III) and (IV)at the end of the polymer chains.

The invention further provides for the use of the inventive vulcanizablerubber compositions for production of rubber vulcanizates, especiallyfor the production of tyres, especially tyre treads, having particularlylow rolling resistance coupled with high wet skid resistance andabrasion resistance.

The inventive vulcanizable rubber compositions are also suitable forproduction of mouldings, for example for the production of cablesheaths, hoses, drive belts, conveyor belts, roll covers, shoe soles,sealing rings and damping elements.

The examples which follow serve to illustrate the invention but have nolimiting effect.

EXAMPLES Example 1a Synthesis of Styrene-butadiene Copolymer,Unfunctionalized (Comparative Example)

An inertized 20 l reactor was charged with 8.5 kg of hexane, 1185 g of1,3-butadiene, 315 g of styrene, 8 mmol of2,2-bis(2-tetrahydrofuryl)propane and 10.3 mmol of n-butyllithium andthe contents were heated to 65° C. Polymerization was effected withstirring at 65° C. for 25 min. Subsequently, 10.3 mmol of cetyl alcoholwere added, the rubber solution was discharged and stabilized byaddition of 3 g of Irganox® 1520(2,4-bis(octylthiomethyl)-6-methylphenol), and the solvent was removedby stripping with steam. The rubber crumbs were dried at 65° C. underreduced pressure.

Vinyl content (IR spectroscopy): 50.2% by weight; styrene content (IRspectroscopy): 20.9% by weight, glass transition temperature (DSC):−25.6° C.; number-average molecular weight M_(n) (GPC, PS standard): 258kg/mol; M_(w)/M_(n): 1.15; Mooney viscosity (ML1+4 at 100° C.): 52 ME

Example 1b Synthesis of Styrene-butadiene Copolymer with Tertiary AminoGroup at the Start of the Chain (Comparative Example)

An inertized 20 l reactor was charged with 8.5 kg of hexane, 1185 g of1,3-butadiene, 315 g of styrene, 11.3 mmol of2,2-bis(2-tetrahydrofuryl)propane, 14.1 mmol of pyrrolidine and 14.1mmol of n-butyllithium, and the contents were heated to 65° C.Polymerization was effected with stirring at 65° C. for 25 min.Subsequently, 14.1 mmol of cetyl alcohol were added, the rubber solutionwas discharged and stabilized by addition of 3 g of Irganox® 1520, andthe solvent was removed by stripping with steam. The rubber crumbs weredried at 65° C. under reduced pressure.

Vinyl content (IR spectroscopy): 50.0% by weight; styrene content (IRspectroscopy): 20.8% by weight, glass transition temperature (DSC):−25.9° C.; number-average molecular weight M_(n) (GPC, PS standard): 210kg/mol; M_(w)/M_(n): 1.19; Mooney viscosity (ML1+4 at 100° C.): 41 ME

Example 1c Synthesis of Styrene-butadiene Copolymer withFunctionalization at the End of the Chain by Reaction withFunctionalization Reagent of the Formula (VII) (Comparative Example)

An inertized 20 l reactor was charged with 8.5 kg of hexane, 1185 g of1,3-butadiene, 315 g of styrene, 8.2 mmol of2,2-bis(2-tetrahydrofuryl)propane and 10.55 mmol of n-butylithium, andthe contents were heated to 65° C. Polymerization was effected withstirring at 65° C. for 25 min. Thereafter, 10.55 mmol (1.69 ml) of2,2,4-trimethyl-[1,4,2]oxazasilinane were added, and the reactorcontents were heated to 65° C. for a further 20 min. Subsequently, therubber solution was discharged and stabilized by addition of 3 g ofIrganox® 1520, and the solvent was removed by stripping with steam. Therubber crumbs were dried at 65° C. under reduced pressure.

Vinyl content (IR spectroscopy): 50.3% by weight; styrene content (IKspectroscopy): 20.9% by weight, glass transition temperature (DSC):−25.7° C.; number-average molecular weight M_(n) (GPC, PS standard): 216kg/mol; M_(w)/M_(n): 1.18; Mooney viscosity (ML1+4 at 100° C.): 44 ME

Example 1d Synthesis of Styrene-butadiene Copolymer with Tertiary AminoGroup at the Start of the Chain and Functionalization at the End of theChain by Reaction with Functionalization Reagent of the Formula (VII)(Inventive)

An inertized 20 l reactor was charged with 8.5 kg of hexane, 1185 g of1,3-butadiene, 315 g of styrene, 11.3 mmol of2,2-bi5(2-tetrahydrofuryl)propane, 14.1 mmol of pyrrolidine and 14.1mmol of n-butyllithium, and the contents were heated to 65° C.Polymerization was effected with stirring at 65° C. for 25 min.Thereafter, 14.1 mmol (2.26 ml) of 2,2,4-trimethyl-[1,4,2]oxazasilinanewere added, and the reactor contents were heated to 65° C. for a further20 min. Subsequently, the rubber solution was discharged and stabilizedby addition of 3 g of Irganox® 1520, and the solvent was removed bystripping with steam. The rubber crumbs were dried at 65° C. underreduced pressure.

Vinyl content (IR spectroscopy): 49.3% by weight; styrene content (IRspectroscopy): 20.3% by weight, glass transition temperature (DSC):−26.3° C.; number-average molecular weight M_(n) (GPC, PS standard): 170kg/mol; M_(w)/M_(n): 1.29; Mooney viscosity (ML1+4 at 100° C.): 43 ME

Examples 2a-d Rubber Compositions

Rubber compositions for tyre treads were produced using thestyrene-butadiene copolymers of Examples 1a-1d.

The constituents are listed in Table 1. The rubber compositions (apartfrom sulphur and crosslinker) were produced in a 1.5 l kneader. Sulphurand accelerator were subsequently mixed in on a roller at 40° C.

Examples 3 a-d Vulcanizate Properties

To determine the vulcanizate properties, the rubber compositions ofExamples 2a-d were vulcanized at 160° C. for 20 minutes. The propertiesof the corresponding vulcanizates are listed in Table 2 as Examples3a-d.

Using the vulcanizates, the following properties were determined:

-   -   resilience at 60° C. (to DIN 33512)    -   abrasion (to DIN 53516)    -   ΔG*: difference between the frequency-dependent viscoelastic        moduli G* at 0.5% elongation and 15% elongation at 60° C/1 Hz        (MTS amplitude sweep)    -   tan δ maximum: maximum dynamic damping in the measurement of the        frequency-dependent viscoelastic modulus at 60° C/1 Hz, where        tan δ=G″/G′ (MTS amplitude sweep)    -   tan δ at 0° C., 60° C.: from the measurement of        temperature-dependent dynamic damping to DIN 53513 (10 Hz,        heating rate 1K·min⁻¹), where tan δ=E″/E′    -   elongation at break, tensile stress at yield (to DIN 53504)

Resilience at 60° C., ΔG*, tan δ maximum (MTS) and tan δ at 60° C. areindicators of the hysteresis loss as the tyre rolls (rollingresistance). The higher the resilience at 60° C. and the lower the ΔG*,tan δ maximum (MTS) and tan δ at 60° C., the lower the rollingresistance of the tyre. Tan δ at 0° C. is a measure of wet skidresistance of the tyre. The higher the tan δ at 0° C., the higher theexpected wet skid resistance of the tyre.

TABLE 1 Constituents of the rubber compositions (figures in phr: partsby weight per 100 parts by weight of rubber) Comparative ComparativeComparative Inventive Example Example Example Example 2a 2b 2c 2dstyrene-butadiene copolymer according to Example 1a 70 0 0 0styrene-butadiene copolymer according to Example 1b 0 70 0 0styrene-butadiene copolymer according to Example 1c 0 0 70 0styrene-butadiene copolymer, according to Example 1d 0 0 0 70 high-cispolybutadiene 30 30 30 30 (BUNA ™ CB 24 from Lanxess Deutschland GmbH)silica (Ultrasil ® 7000) 90 90 90 90 carbon black (Vulcan ® J/N 375) 7 77 7 TDAE oil (Vivatec 500) 36.3 36.3 36.3 36.3 processing aid 3 3 3 3(Aflux 37 from Rheinchemie Rheinau GmbH) stearic acid (Edenor C 1898-100) 1 1 1 1 ageing stabilizer 2 2 2 2 (Vulkanox ® 4020/LG fromLanxess Deutschland GmbH) ageing stabilizer 2 2 2 2 (Vulkanox ® HS/LGfrom Lanxess Deutschland GmbH) zinc oxide (Rotsiegel zinc white) 3 3 3 3wax (Antilux 654) 2 2 2 2 silane (Si 69 ® from Evonik) 7.2 7.2 7.2 7.2diphenylguanidine (Rhenogran DPG 80) 2.75 2.75 2.75 2.75 sulphenamide(Vulkacit ® NZ/EGC from Lanxess 1.6 1.6 1.6 1.6 sulphur (Chancel 90/95ground sulphur) 1.6 1.6 1.6 1.6 sulphonamide (Vulkalent ® E/C) 0.2 0.20.2 0.2

TABLE 2 vulcanizate properties Comparative Comparative ComparativeInventive Example Example Example Example 3a 3b 3c 3d ComparativeExample 2a X Comparative Example 2b X Comparative Example 2c XComparative Example 2d X Vulcanizate properties: Resilience at 60° C.[%] 56.2 57.2 58.7 59.2 ΔG* (G*@0.5% − G*@15%) [MPa] 1.37 1.37 1.08 0.78tan δ maximum (MTS amplitude sweep at 1 Hz, 60° C.) 0.173 0.161 0.1560.141 tan δ at 0° C. (dynamic damping at 10 Hz) 0.269 0.263 0.279 0.294tan δ at 60° C. (dynamic damping at 10 Hz) 0.103 0.093 0.085 0.077Elongation at break (S2 specimen) [%] 457 414 449 422 Tensile stress atyield (S2 specimen) [MPa] 19.4 18.6 20.8 20.4 Abrasion (DIN 53516) [mm³]69 70 74 73

Tyre applications require a low rolling resistance, which exists when ahigh value for resilience at 60° C. and a low tan δ value in dynamicdamping at high temperature (60° C.), and a low tan δ maximum in the MTSamplitude sweep, are measured in the vulcanizate. As is clear from Table2, the vulcanizate of Inventive Example 3 d is notable for highresilience at 60° C., a low tan δ value in dynamic damping at 60° C. anda low tan δ maximum in the MTS amplitude sweep.

Tyre applications additionally require a low wet skid resistance, whichexists when the vulcanizate has a high tan δ value in dynamic damping atlow temperature (0° C.). As is clear from Table 2, the vulcanizate ofInventive Example 3 d is notable for a high tan δ value in dynamicdamping at 0° C.

1. Diene polymers comprising, at the start of the polymer chains,tertiary amino groups of the formula (I) or (II)

where R¹, R² are the same or different and are each alkyl, cycloalkyl,aryl, alkaryl and aralkyl radicals which may contain heteroatoms, Z is adivalent organic radical which, as well as C and H, may containheteroatoms and, at the end of the polymer chains, silane-containingcarbinol groups of the formula (III)

or metal salts thereof or semimetal salts thereof, where R³, R⁴, R⁵, R⁶are the same or different and are each an H or alkyl, cycloalkyl, aryl,alkaryl and aralkyl radicals which may contain heteroatoms, and A is adivalent organic radical which, as well as C and H, may containheteroatoms.
 2. The diene polymers according to claim 1, wherein thesilane-containing carbinol groups of the formula (III) at the end of thepolymer chains of the diene polymers are in the form of metal salts ofthe formula (IV)

where R³, R⁴, R⁵, R⁶ are the same or different and are each an H oralkyl, cycloalkyl, aryl, alkaryl and aralkyl radicals which may containheteroatoms, A is a divalent organic radical which, as well as C and H,may contain heteroatoms, n is an integer from 1 to 4, M is a metal orsemimetal of valency 1 to
 4. 3. The diene polymers according to claim 1or 2, wherein the diene polymer is a polybutadiene, a polyisoprene, abutadiene-isoprene copolymer, a butadiene-styrene copolymer, anisoprene-styrene copolymer or a butadiene-isoprene-styrene terpolymer.4. The diene polymers according to claim 1, wherein: the heteroatoms areselected from the group consisting of O, N, S, Si, and any combinationthereof, and M is selected from the group consisting of Li, Na, K, Mg,Ca, Fe, Co, Ni, Al, Nd, Ti, Si, Sn, and any combination thereof.
 5. Thediene polymers according to claim 1, wherein: the diene polymers havemean molar masses (number-average) of 10000 to 2000000 g/mol, the dienepolymers have glass transition temperatures of −110° C. to 20° C., andthe diene polymers have Mooney viscosities of 10 to 200 Mooney units. 6.The diene polymers according to claim 1, wherein: the diene polymershave mean molar masses (number-average) of 100000 to 1000000 g/mol, thediene polymers have glass transition temperatures of preferably −110° C.to 0° C., and the diene polymers have Mooney viscosities of 30 to 150,Mooney units.
 7. Process for preparing diene polymers according to claim1, comprising: introducing functional groups at the end of the polymerchains by reaction with functionalization reagents of are one or more1-oxa-2-silacycloalkanes, and introducing the tertiary amino groups atthe start of the polymer chains by reaction with alkali metal amides ofsecondary organic amines of the general formula (V) or (VI)

where R¹, R² are the same or different and are each alkyl, cycloalkyl,aryl, alkaryl and aralkyl radicals which may contain heteroatoms, Z is adivalent organic radical which, as well as C and H, may containheteroatoms, and M is Li, Na, K.
 8. The process according to claim 7,wherein the 1-oxa-2-silacycloalkanes are compounds of the generalformula (VII)

where R³, R⁴, R⁵, R⁶ are the same or different and are each H, alkyl,cycloalkyl, aryl, alkaryl and aralkyl radicals which may containheteroatoms, and A is a divalent organic radical which, as well as C andH, may contain heteroatoms.
 9. The process for preparing diene polymersaccording to claim 7, further comprising: obtaining alkali metal amidesby reaction of secondary organic amines with organo-alkali metalcompounds in situ or in a separate preforming step, and reacting,reactive ends of the polymer chains with one or more1-oxa-2-silacycloalkanes.
 10. The process according to claim 7, whereinthe 1-oxa-2-silacycloalkanes are added after completion of thepolymerization.
 11. The process according to claim 9, wherein, thealkali metal amides are used as anionic polymerisation initiators. 12.The process according to claim 9, wherein the secondary organic aminesused are pyrrolidine or hexamethyleneimine, and the organo-alkali metalcompound is butyllithium.
 13. The process according to claim 9, wherein:the molar amount of secondary amines is less than or equal to the molaramount of organo-alkali metal compounds, and amount of1-oxa-2-silacycloalkanes is between 0.005-2% by weight, based on theamount of polymer having reactive ends of the polymer chains.
 14. Theprocess according to claim 9, wherein: the ratio of the molar amount ofsecondary amines to the molar amount of organo-alkali metal compounds is0.05-2.00:0.05-2.00, and the amount of 1-oxa-2-silacycloalkanes isbetween 0.005-2% by weight, preferably between 0.01-1% by weight, basedon the amount of polymer having reactive ends of the polymer chains. 15.The process according to claim 7, wherein coupling reagents are used forthe reaction.
 16. A method for producing vulcanizable rubbercompositions, the method comprising producing the vulcanizable rubbercompositions from diene polymers according to claim
 1. 17. Vulcanizablerubber compositions obtained according to claim 16, wherein thevulcanizable rubber compositions additionally comprise ageingstabilizers, oils, fillers, rubbers and/or rubber auxiliaries. 18.Vulcanizable rubber compositions comprising diene polymers according toclaim 1 or
 2. 19. Vulcanizable rubber compositions comprisingfunctionalized diene polymers having tertiary amino groups of theformula (I) or (II) at the start of the polymer chains and functionalgroups of the formula (III) at the end of the polymer chains accordingto claim
 1. 20. Vulcanizable rubber compositions comprisingfunctionalized diene polymers having tertiary amino groups of theformula (I) or (II) at the start of the polymer chains and functionalgroups of the formula (IV) at the end of the polymer chains according toclaim
 2. 21. Vulcanizable rubber compositions comprising functionalizeddiene polymers having tertiary amino groups of the formula (I) or (II)at the start of the polymer chains and functional groups of the formula(III) and (IV) at the end of the polymer chains according to claim 2.22. A method for producing tyres, the method comprising producing atleast tyre tread of the tyres from the vulcanizable rubber compositionsaccording to claim
 19. 23. A method for producing moulded articles, themethod comprising producing moulded articles from the vulcanizablerubber compositions according to claim
 19. 24. Tyres obtainableaccording to claim
 22. 25. Moulded articles obtainable according toclaim 23, wherein the moulded articles comprise cable sheaths, hoses,drive belts, conveyor belts, roll covers, shoe soles, sealing rings anddamping elements.